Yamaha YSR50

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Yamaha YSR50
Production 87-93
49.3cc 2-stroke, single cylinder, air-cooled with reed valve
Bore / Stroke 40.0mm x 39.2mm
Compression ratio 7.4:1
Top Speed 38 mph
Horsepower 7 horsepower @ 8,800 RPM
Torque 0.59 kg-m @ 8,500 RPM
Fuel System Carburetor, Mikuni VM16SH
Spark Plug NGK B8HS '87-93
Battery YUASA 6N4-2A-2 '87-93
Transmission 5-speed constant mesh
Final Drive Chain: 420x100
Front Sprocket 12T
Rear Sprocket 44T
Front Tire 3.50-12 '87-93
Rear Tire 4.00-12 '87-93
Wheelbase 1050mm
Length 1575mm
Width 635mm
Height 930mm
Seat Height 650mm
Weight 75kg (dry),
Recommended Oil Yamalube 10w-40
Related Yamaha RX50 (contained same engine), Yamaha YSR80
Competition Honda NSR50, Aprilia RS50
Manuals Service Manual

Brochures ·

The Yamaha YSR50 is a motorcycle produced by Yamaha from 1987 to 1993.

This style of miniature motorcycle is known as a pocket bike. Although small in size, these machines are capable of giving surprising performances in the hands of skilled operators. Enthusiast groups organize races and endurance runs for pocket-bikes, of which the YSR Yamaha is the most popular. It mainly competes with the likes of the Honda NSR50. The limited edition Yamaha RX50 shared the same engine.


Yamaha YSR 50 and YSR 80 sport models goes on sale in Japan in 1986, and had the look of a re-shaped, scaled-down YZR500 factory racer that appealed to the spirit of race enthusiasts. The 2-stroke single-cylinder engine had a maximum output of 7 ps for the 50cc and 8.8 ps for the 80cc, a return type 5-speed transmission, front disc brake and other features to offer full-fledged sport riding potential. It became a standard in the mini-bike races popular at the time. 1992 was the last year of production, and the price was 189.000 yen for the 50cc and 211.000 yen for the 80cc.





1992 Yamaha YSR50